Three Phase Line & Load Regulation using SCR and

Microcontroller

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Introduction

Project Objective

General Introduction

Project Introduction

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Objective

To upgrade the existing three phase analog regulatory system, to a three phase, microcontroller based SCR drive system. So that if any fluctuation comes in three phase voltage supply, controller will Sense that fluctuation and accordingly give triggering pulses to the SCR to get controlled regulated output at the load.

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General Introduction In our day to day life we use a lot of electronic devices to satisfy our needs or to make our life comfortable and luxurious.

Every device needs a power supply, to work on. And for the optimum functioning of the device it is necessary that the supply should be reliable.

That is, it should provide a constant voltage. But this is not possible always.

Next

There are many reasons due to which there is a fluctuation in the supply voltage. This change in the supply voltage may cause the device to damage.

The best alternative is to regulate the supply voltage. This is what we have tried to achieve here.

Regulation is a process to maintain the output of a circuit at a constant desired level irrespective to the variation in the input.

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Project Introduction

Load has a constant voltage of 220 V dc., in spite of any variation in the input voltage.

The voltage regulation is achieved by controlling the firing angle of the SCR.

The voltage across the load is stepped down and provided to ADC.

This digital signal from ADC is then processed by the controller and generates a firing pulse for SCR, hence controlling the load current.

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• Block Diagram

• Block Diagram Description

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POWERSUPPLY

SCR BRIDGE CKT

230V AC

ADC

ZEROCROSSINGDETECTOR

24V AC

CLOCK & RESET CKT

O/P

MICRO-CONTROLLER

POTENTIAL DIVIDER

Block Diagram Description

POWER SUPPLY

ZERO CROSSING DETECTOR

SCR BRIDGE NETWORK

POTENTIAL DIVIDER

ANALOG TO DIGITAL CONVERTER (ADC 0808)

MICROCONTROLLER 89C51RD2

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Power Supply

• Center tapped step down transformer with rating 240V to 24V and 500mA.

• Regulator LM7805 for 5V supply.

• Regulator MC7815C for 15V supply to op-amp.

• Regulator L7915 for -15V supply to op-amp.

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Zero Crossing Detector

• Used for synchronization with input mains supply.

• OP-AMP UA 741 is used.

• Supply is given from regulators to OP-AMP.

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SCR Bridge

Consist of:

• Two pair of SCR in a bridge form, i.e. each two in series

• And a load (assumed resistive, 10k ohm)

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Potential Divider

• Provides feedback to ADC

• Uses the ratio is 59:1

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Analog to Digital Converter

• Input dc analog from Potential divider

• Output digital to microcontroller

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Micro-controller

• The only Decision making block of the system

• Takes decision of the firing angle of the SCR

• Acts as a comparator

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• Circuit Diagram

• Component Specifications

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Circuit Diagram & Component Specification

R 7

1 k

D 8

DIO

DE

C 2

10uf

T1

TR

AN

SF

OR

ME

R C

T

1 5

6

4 8

D 7

DIO

DE

2

-

+ U 8

UA

741C

3

26

7 14 5

Q 1S C R

U 2 L M 7 8 0 5

1 3V I N V O U T

D 1 D I O D E

U 9

AD

C08

08 7

1 0

1 1

1 21 6

2 2

2 32 42 5

2 62 72 8

12345

96

1 71 41 581 81 92 02 1

E O C

C L K

V C C

+V R E F-V R E F

A L E

A D D CA D D BA D D A

I N 0I N 1I N 2I N 3I N 4I N 5I N 6I N 7

O ES TA R T

D B 0D B 1D B 2D B 3D B 4D B 5D B 6D B 7

VCC

V C C

Y 1

20 M

HZ

C 3

0.1u

f

R 21 k

1

D 4 D I O D E

+5V

R 21 k

C 71 0 u f

U 6

M C 7 8 1 5 C1 3

V I N V O U T

R 6R 3

1 0 k

R 18 . 2 k

V C C

R 4

R4

+ R

5 +

R6

= 59

K

+15v

R 5

C 6 3 0 p f

-15v

C 53 0 p f

D 6D I O D E

24v DC

U 7L 7 9 1 5

2 3V I N V O U T

D 2D I O D E

D 3D I O D E C 4

0.1u

f

240v ac

Q 2S C R

P 2 . 5C 51 0 u f

U 3

89

C5

1

9

1 81 9

2 93 0

3 1

12345678

2 12 22 32 42 52 62 72 8

1 01 11 21 31 41 51 61 7

3 93 83 73 63 53 43 33 2

R S T

XTA L 2XTA L 1

P S E NA L E / P R O G

E A / V P P

P 1 . 0P 1 . 1P 1 . 2P 1 . 3P 1 . 4P 1 . 5P 1 . 6P 1 . 7

P 2 . 0 / A 8P 2 . 1 / A 9

P 2 . 2 / A 1 0P 2 . 3 / A 1 1P 2 . 4 / A 1 2P 2 . 5 / A 1 3P 2 . 6 / A 1 4P 2 . 7 / A 1 5

P 3 . 0 / R XDP 3 . 1 / TXD

P 3 . 2 / I N T0P 3 . 3 / I N T1

P 3 . 4 / T0P 3 . 5 / T1

P 3 . 6 / W RP 3 . 7 / R D

P 0 . 0 / A D 0P 0 . 1 / A D 1P 0 . 2 / A D 2P 0 . 3 / A D 3P 0 . 4 / A D 4P 0 . 5 / A D 5P 0 . 6 / A D 6P 0 . 7 / A D 7

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Component Specification

• Regulators LM7805, MC7815, L7915

• Diodes 1N4007

• Op-Amp UA741

• Analog to Digital Converter ADC0808

• Micro-Controller P89C51RD2

• SCR MCR100-6

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LM7805

• 3-Terminal Regulators

• Output Current up to 1.5 A

• Internal Thermal-Overload Protection

• Input voltage 35v max

• Operating virtual junction temperature, 150C

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MC7815

• Output Current in Excess of 1.0 A

• No External Components Required

• Internal Thermal Overload Protection

• Internal Short Circuit Current Limiting

• Temperature Range of –40°C to +125°C

• Standard 3–Lead Transistor Packages

• Input voltage 40V dc Max

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L7915

• Output Current up to 1.5A

• Thermal overload protection

• Short circuit protection

• Input voltage 40V dc Max

• Standard 3–Lead Transistor Packages

Back

Back

Diode• High surge current capability.

• Peak repetitive reverse voltage 1000 V

• Average rectified forward current 1A

• Operating junction temperature -55 to +175 C

• Power dissipation 3 W

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Op-amp

• Large Input Voltage range• High gain• Short-Circuit protection• Supply voltage +/- 22V• Input voltage +/- 15V• Power dissipation 500mW

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Microcontroller• 80C51 Central Processing Unit.• On-chip Flash Program Memory with In-System Programming (ISP) and In-Application Programming (IAP) capability• 6 clocks per machine cycle operation (standard)• Speed up to 20 MHz with 6 clock cycles per machine cycle(40 MHz equivalent performance)• RAM expandable externally to 64 kB• 4 level priority interrupt• Four 8-bit I/O ports. Pin diagram• Power control modes - Clock can be stopped and resumed - Idle mode - Power down mode

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MCR 100-6

• Blocking Voltage to 600 V.

• ON State Current Rating of 0.8 Amperes.

• Latching Current is typ. 0.6 mA and max. 10 mA.

• Holding Current is typ. 0.5 mA and max. 5 mA.

• High Surge Current Capability 10 A.

• SCR Characteristics

• 3–Lead Transistor Packages Back

Voltage Current characteristic of SCR

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ADC 0808• 8-channel multiplexer with address logic.

• 0V to 5V input range with single 5V power supply.

• Resolution 8 bits.

• Conversion time 100 us.

• Voltage at Control Inputs -0.3V to +15V

Pin Diagram Back

Back

Back

D 6D I O D E

-15v

C 2

10uf

T1

TR

AN

SF

OR

ME

R C

T

1 5

6

4 8

V C C

24v DC

R 21 k

Y 1

20 M

HZ

V C C

R 18 . 2 k

Q 1

S C R

240v ac

R 21 k

P 2 . 5

R 3

1 0 k

U 9

AD

C08

08 7

1 0

1 1

1 21 6

2 2

2 32 42 5

2 62 72 8

12345

96

1 71 41 581 81 92 02 1

E O C

C L K

V C C

+V R E F-V R E F

A L E

A D D CA D D BA D D A

I N 0I N 1I N 2I N 3I N 4I N 5I N 6I N 7

O ES TA R T

D B 0D B 1D B 2D B 3D B 4D B 5D B 6D B 7

C 4

0.1u

f

D 4 D I O D E

C 53 0 p f

D 3D I O D E

U 6

M C 7 8 1 5 C1 3

V I N V O U T

C 3

0.1u

f

C 71 0 u f

U 7L 7 9 1 5

2 3V I N V O U T

2

C 6 3 0 p f

D 2D I O D E

C 51 0 u f

U 3

89

C5

1

9

1 81 9

2 93 0

3 1

12345678

2 12 22 32 42 52 62 72 8

1 01 11 21 31 41 51 61 7

3 93 83 73 63 53 43 33 2

R S T

XTA L 2XTA L 1

P S E NA L E / P R O G

E A / V P P

P 1 . 0P 1 . 1P 1 . 2P 1 . 3P 1 . 4P 1 . 5P 1 . 6P 1 . 7

P 2 . 0 / A 8P 2 . 1 / A 9

P 2 . 2 / A 1 0P 2 . 3 / A 1 1P 2 . 4 / A 1 2P 2 . 5 / A 1 3P 2 . 6 / A 1 4P 2 . 7 / A 1 5

P 3 . 0 / R XDP 3 . 1 / TXD

P 3 . 2 / I N T0P 3 . 3 / I N T1

P 3 . 4 / T0P 3 . 5 / T1

P 3 . 6 / W RP 3 . 7 / R D

P 0 . 0 / A D 0P 0 . 1 / A D 1P 0 . 2 / A D 2P 0 . 3 / A D 3P 0 . 4 / A D 4P 0 . 5 / A D 5P 0 . 6 / A D 6P 0 . 7 / A D 7

R 4

R4

+ R

5 +

R6

= 5

9K

U 2 L M 7 8 0 5

1 3V I N V O U T

R 5

1

R 6Q 2S C R

VCC

+5V

P 2 . 5

R 8

1 k

D 1 D I O D E

Q 4S C R

+15v

Q 3S C R

-

+ U 8

UA

741

C

3

26

7 14 5

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Three Phase Line & Load Regulation using SCR and

Microcontroller

FLOW CHARTS

• Main Program (Flow-chart & Code)

• Read Output of ADC

• Pulse Width Calculation

• Delay Calculation for Firing Pulse

• Delay for Firing Pulse Back

Three Phase Line & Load Regulation using SCR and

Microcontroller

Start

End

Set timer in mode zero

Load timer with ADC Val.

Start timer

Stop timer

Reset timer flag

Is TF=1

No

Yes

Back

Start

Get value for timer

register from look-up table

End

Back

Start

Reset timer flag

Stop timer

Start timer

Load timer register

Set timer in mode zero

Is TF=1

End

Yes

No

Back

Start

Activate SOC

Monitor EOC

Activate output enable

ActivateALE

End

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A

Set port pin P2.1

Delay for firing pulse

Delay calc. for firing pulse

Read output from ADC

Is ZCD=1

Reset port pin P2.1

Pulse width delay

R

Yes

No

Back

START

Set port P1 as input port

Read output of ADC

Delay calc. for firing pulse

Delay for firing pulse

Set port pin P2.0

Pulse width delay

Reset port pin P2.0

Is ZCD=1

A

R

No

Yes

Next

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Conclusion

We designed hardware for voltage regulation by using SCR Bridge, which senses fluctuations in the single-phase input mains supply across the load and nullifies it.

Hence our device is capable of regulating the single-phase mains supply to a constant dc supply across the load, irrespective of any changes in the supply, hence providing protection to the load device from getting damaged due to sudden variations in the mains.

Next

Future Enhancement

To implement the line and load regulation of three phase supply.

Implementation of ARM co-processor in place of micro-controller 89C51RD2.

Next

Thank you

unsigned int delay_calc(){ unsigned char i,ip=0; unsigned int hex_value=0; code unsigned char ip_adc[ ]={0xC2, 0xC3, 0xC4, 0xC5, 0xC6, 0xc7, 0xC8, 0xC9, 0xCA, 0xCB, 0xCC, 0xCD, 0xCE, 0xCF,

0xD0, 0xD1, 0xD2, 0xD3, 0xD4, 0xD5, 0xD6, 0xD7, 0xD8, 0xD9, 0xDA, 0xDB, 0xDC, 0xDD, 0xDE, 0xDF, 0xE0, 0xE1, 0xE2, 0xE3, 0xE4, 0xE5, 0xE6, 0xE7, 0xE8, 0xE9, 0xEA, 0xEB, 0xEC, 0xED, 0xEE, 0xEF, 0xF0, 0xF1, 0xF2, 0xF3, 0xF4, 0xF5, 0xF6, 0xF7, 0xF8, 0xF9,

0xFA, 0xFB, 0xFC, 0xFD, 0xFE, 0xFF}; code unsigned int tmod_value[ ]={0xFD1D, 0xFBDE, 0xFAED, 0xFA23, 0xF972, 0xF8D4, 0xF843,

0xF7BC, 0xF73F, 0xF6C9, 0xF659, 0xF5EF, 0xF58A, 0xF529, 0xF4CC, 0xF472, 0xF41B, 0xF3C8, 0xF377, 0xF329, 0xF2DD, 0xF293, 0xF248, 0xF205, 0xF1C0, 0xF17E, 0xF13C, 0xF0FD, 0xF0BF, 0xF082, 0xF046, 0xF00C, 0xEFD3, 0xEF9A, 0xEF63, 0xEF2D, 0xEEF8, 0xEEC4, 0xEE91, 0xEE5F, 0xEE2D, 0xEDFD, 0xEDCD, 0xED9D, 0xED6F, 0xED41, 0xED14, 0xECE8, 0xECBC, 0xEC91, 0xEC66, 0xEC3D, 0xEC13, 0xEBEA, 0xEBC2, 0xEB9A,

0xEB73, 0xEB4C, 0xEB26, 0xEB00, 0xEADB, 0xEAB6};ip=P1;if(ip>0xC1){ for(i=0;i<62;i++)

{ if(ip==ip_adc[i]) { hex_value=tmod_value[i];

break; } }} else{hex_value=0xFFFF;}return(hex_value);

}

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sbit trigger1=P2^0;

sbit trigger2=P2^1;

sbit soc=P2^2;

sbit eoc=P2^3;

sbit oe=P2^4;

sbit zcd=P2^5;

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unsigned char ADC(void);

void delay_trigger(void);

unsigned int delay_calc(void);

void angle_delay(unsigned char, unsigned char);

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unsigned char ADC(void){

oe=1;

soc=1;LOOP_5:

soc=0;if(soc==1)goto LOOP_5;

while(eoc==1);

oe=0;return(0);

}

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void delay_trigger(){

TMOD=0x01;TH0=0xF9;TL0=0x7D;TR0=1;while(!TF0);TR0=0;TF0=0;

}

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void angle_delay(unsigned char tl0, unsigned char th0){

TMOD=0x01;TL0 = tl0;TH0 = th0;TR0 = 1;while(!TF0);TR0 = 0;TF0 = 0;

}

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#include <stdio.h>#include <reg51.h>#include <set_bit.h>#include <func_declaration.h>#include <ADC.h>#include <delay_trigger.h>#include <angle_delay.h>#include <delay_calc.h>void main(){ unsigned int b; unsigned char tl0,th0;do{ P1=0x0ff;

ADC();b = delay_calc();tl0 = b;b = b&0xFF00;b = b>>8;th0=b;while(!zcd);angle_delay(tl0,th0);

LOOP_2:trigger1=1;if(!trigger1)goto LOOP_2;

delay_trigger(); //turn on time delay(pulse width)tot=1000us.

Next

LOOP_3: trigger1=0;if(trigger1)goto LOOP_3;

ADC();b = delay_calc();tl0 = b;b = b&0xFF00;b = b>>8;th0=b;while(zcd);angle_delay(tl0,th0);LOOP_4: trigger2=1;

if(!trigger2)goto LOOP_4;

delay_trigger(); //turn on time delay(pulse width)tot=1000us.

LOOP_5: trigger2=0;if(trigger2)goto LOOP_5;

}while(1);}

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